In absorbent articles of known type, the main body of the article has a front end portion, also referred to simply as “front” in the jargon of the trade and which, in use, as this implies, covers a front part of the wearer's body, and a back end portion, also referred to simply as “back” in the jargon of the trade and which, in use, as this implies, covers a back part of the wearer's body.
These articles comprise a pair of panels or side wings, which may, if necessary, consist of two or more connected parts, which extend from opposite sides of the front end portion and which are called “front panels” in the jargon of the trade, and a pair of panels or side wings, which may, if necessary, consist of two or more connected parts, which extend from opposite sides of the back end portion and which are called “back panels” in the jargon of the trade.
This invention is applicable in the stations for assembling the absorbent sanitary article, where the panels, or wings, are applied to the main body, and that is to say, to a continuous web which, when the product is finished, defines the “top sheet” (permeable layer) or the “back sheet” (impermeable layer) of the main body, or “chassis”, of the article.
In the prior art, units for forming the absorbent article are defined by a drum with which are associated means for feeding a succession of pairs of panels, or wings, and means for feeding at least one continuous web of material.
In some embodiments, the means for feeding the succession of pairs are subdivided into two wheels, or arms, each configured to apply pairs of front or back panels, typically differing in shape and composition.
Whatever the case, prior art units generally comprise an adhesive applicator unit configured to apply a predetermined quantity of adhesive on the panels or on the web at a panel coupling zone.
More specifically, this unit is configured to release enough adhesive to position the panel “provisionally” but not to fix it permanently.
In effect, prior art units are provided with a sealing station located downstream of the drum and equipped with a plurality of sonotrodes facing an abutment surface (or anvil) where the panels, positioned by means of the adhesive, are fixed securely to the web at two or more points.
Disadvantageously, the presence of an adhesive applicator unit introduces several critical factors and complications in the machine.
In effect, the ultrasonic sealing station, located after the adhesive applicator unit, tends to overheat the adhesive, melting it and causing it to seep into the absorbent article.
Moreover, the melted adhesive does not affect only the absorbent article but tends to contaminate the sealing station as a whole, especially the sonotrode, or anvil, thus increasing maintenance costs and machine down times.